Process for producing an electroconductive sound wave record



H. L. PAGE I1,840,791

PROCESS FOR PRODUGING AN ELECTROCONDUCTIVE SOUND WAVE RECORD Jan. 12,1932.

Filed Aug. 3, 1928 3 'Sheets-Sheet DUUDnnnnH-n.

m vn.. L

d o n Jan. 12', 1932. H, .PAGE y 1,840,791

PROCESS FOR PRODUCING AN ELECTROCONDUCTIVE SOUND WAVE RECORD Filed Aug.3, 1928 5 Sheets-Sheet 2 @a vwentoz H. L. PAGE Jari. 12, 1932.

PROCESS FOR PRODUCING AN ELECTHOCONDUCTIVE SOUND WAVE RECORD Filed Aug.f5, 1928 3 Sheets-Sheet 5 gwn/@y 8mm/141601 Patented Jan. 12, 1932UNITED STATES PATENT `ol-Flca HOWARD L. PAGE, oF CHICAGO, ILLrNoIsrnocnssron PRonUciNG AN Etnc'rnocoNDUcrrvEsoUNn WAVE RECORD Appncauqnmed August 3,' 192s. serial no. 297,333.

This invention relates to improvements in sound records either ofthefilm or pliable tape type or of' the rigid type similar for example tothe phonograph disc record but will be l described herein for purposesofillustration only with reference to the pliable tape type which may bewound on a reel like aj motion picture film for example. v

It is anV object ofthe invention to provide a. sound record, which maybe produced and reproduced either separately o r synchronously, with theproduction or the reproduction of motion pictures. Further ob'ects ofthe invention are the production o sound l5 records which areelectroconductiveand the reproduction of the sounds recorded on such`arecord- Itis a further object of the invention to 2 vproduce ametallic sound record which is elecproperties are utilized inthereproduction of sound from such record.

It is another object of the invention to produce an electroconductivesound record from `tions .may easily bemade. With these and otherobjects in `view the invention consists v for example in a tape or filmonwhich sound waves are recorded in a novel manner by a l `specialphotographic process. The `invention further consists of many Yfeaturesand details of construction which will be hereinafter more fullydescribed and finally pointed out in the appended claims and whichareillustrated on the accompanying drawings I which form a material partof this disclosure and `in which:

Fig. 1 shows a film'provided with one metroconductive and whichvelectroconductivel which aplurality of commercial 'reproduc-f ofV acollodion coated 1ilm` representing the sound 'record made by myinvention.

Fig` 5 is a section similar tothat of Fig. 4 illustrating forcomparative purposes the distribution of silver particles in a gelatincoated' 55 film on which a sound record has been photographed. y

Fig. ,6 is a diagrammatic plan of a camera -for photographing soundrecords such ash shown in Fig. 1.

Fig. 7 is a diagrammatic plan of -a camera for simultaneouslyphotographing motion picture images and a sound record on the same film'suchY as shown in Fig. 2. Fig. 8 is a perspective view of an apparatus'suitable for producing duplicates of the f sound records shown. f

-Fig.'9 is a plan view of an original negative gelatin film with twosound wave record lines thereon. Fig-10 is a plan view of apositivemaster Vfilm printed from the negative shown in Fig.r9 and utilized inthe making of the final sound record of this invention. Y

The sound recording cameras shown in '75 lFigs; :6 and 7 areself-explanatory to those familiar with the artand are shown as anapparatus for `producing the original sound negative which is developedin the usual way and becomes'the negative which is fixed in'fhyposulphite .of sodium solution and dried in a `suitable manner. r

Fig. 9 shows a developed negative 401 of a sound wave film. The soundWave formation appears opaque thereon in the clear gela-755 tin ycoatingof the film. From this negative a positive film 40m Fig. 10 is printedby the ordinary contact printing method on the 'usual positive gelatincoated film. This positive sound record allows light to pass through itexactly where the original sound wave photograph was Aand this film isused as a master film for the production of commercial sound recordfilms.

The commercial sound record `films are produced in the apparatus shownin Fig, 8.

Vand when finished these records have the sound Wave lines and the baselines thereon Y in the form or nature of a metallic depositen ,thesurface of the-film. The sound record film material does not need to betransparent .for reproduction of sound waves; I have used paperreinforced by cloth with good success. Only films 60 shown in Fig. 7which have also a motion picture imprinted thereon require transparentfilm and these only for projection of the picture. y

The process and apparatus for producing metallic sound wave lines fromthe positive master film is as follows:

In a box-like housing 61, (see Fig. 8) a lamp 62 is mounted in front ofa concave reflector 63 which concentrates the light from the lamp 62onto a lens system 64 and onto the positive master lm 40m which iscarried by suitable reels 65 and 66. The light after passing throughpositive master film 40m is focussed through a narrow slot 67a by a lenssystem 67 onto a sensitized surface such as the face of film 70. Thisfilm 7() need not be transparent as mentioned before nor is a gelatincoating required.

I have secured excellent results by coating the surface of the film 7 OWith other light sensitive materials such as for example a coating ofcollodion in which iodides or bromides of either or both cadmium orammonium have been dissolved. While I secure good results with thesematerials, nevertheless, others which act in a similar way may beemployed. The film strip with its prepared surface is held on a storagereel 68 in the lower part of housing 61 and passes from there underroller G9, rotatably mounted in a trough 71. This trough contains asolution of silver nitrate of suitable strength to react with thebromides or iodides carried by the collodion or other vehicle. Inpractice a nitrate solution of thirty grains of silver nitrate to theounce of water has been found satisfactory. The film then passes over aroller 7 2 and while still wet receives the developable light impressionfrom lamp 62 which has passed through master film 40m bearing the soundWave line thereon. Reel 65 and roller 73 are suitably connected by achain drive causing them to rotate synchronously either at thesame speedor at different speed ratios. If desired, however, the film may first bedried and then a Contact print made from the master film 40m, theexposure of the film while wet, i. e., before drying as above describedbeing merely by way of illustration. Such dry collodion films are morefully described by E. J. Wall in his Photographic Emulsions, 1929, page112.

A Film 70 after passing over roller 73 then passes under a roller 74rotatably mounted in trough 75 which contains a solution of ferroussulphate and acetic acid which develops the image of the sound wave lineon the film. I have obtained good results by the use of a developercomposed of thirty grains of ferrous sulphate to one ounce of water andtwenty minims of acetic acid. The

record film 70 then passes over a roller 7 6 and under roller 78 whichlatter roller is mounted in trough 77 containing a fixing solution ofsodium hyposulphite which dissolves the un` exposed silver particles,whereupon the film 70 passes out of housing 61 over roller 7 9 and underroller 80 to any suitable drying appa.- ratus.

That part of the record film 70 so produced which has been exposed asprecipitated and developed thereon metallic silver, thereby producing anelectroconductive metallic record of the sound wave on the film as shownin enlarged section in Fig. 4.

This action is covered in greater detail by Meldola in his work TheChemistry of Photography 4th ed., 1913, page 159; also by Abney in hisInstruction in Photography 11th ed., 1905, page 32.

Fig. 5 represents a sectional elevation through a celluloid support 82which carries the usual gelatine emulsion 83 and contains materialssensitive to light held in suspension within the emulsion. Whendeveloped with the usual alkaline developer the opaque particlesrepresenting the images are distributed or diffused throughout the totalthickness of the film as indicated at c1, d2 and cl3. The electricalconductivity of such a record is negligible, the metallic particlesbeing insulated from each other by the gelatine. The use of the aciddeveloper above referred to is, therefore, of great and materialadvantage in that it enables me to produce an electroconductive soundrecord as distinguished from a sound record which is notelectroconductive, the production of an electroconductive sound recordbeing a desideratum of my invention.

Fig. 4 shows a similar cross section through the same sound record filmof Fig. 3 when produced by my method. The support 82 carries a coatingof collodion 84 upon the surface of which lies the image of the soundwave c and base lines d-dl as a coating of metallic silver the particlesof which are adjacent to each other and s'o close that they form anexcellent conductor of electricity, and what is of greatest importancethe sound wave and base lines are all on the surface of the coatingforming accessible contact surfaces Which are insulated from each otherby the collodion coating 84 between them and the support 82 below them.

The metallic deposit on the supporting base may be increased inthickness if desired by redevelopment with a liquid containing a metalin solution which can be precipitated therefrom and deposited upon themetallic image. While a certain percentage of gelatine may beincorporated in the carrier or supporting base and such a film treatedwith the developers above referred to, the results do not seem to beimproved.

The method for reproduction of sound from my metallic sound record is avery simple one as the metal of the record itself is capable of varyingthe current in an electric circuit.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. The process fork producin an electroconductive sound wave record wich consists in photographically recordin sound Waves upon a transparentfilm, pro ucing a negative image of the sound waves by developing saidfilm, printing a positive therefrom, reprinting said record upon adielectric tape having a coating containing a metallic compound, andprecipitating the metal from said compound on to the surface of saidtape by photographic development.

Q. The process lfor producing an electroconductive sound Wave recordwhich consists in photographically recording sound Waves upon atransparent film, producin a negative image of the sound Waves by deveoping said film, printing a positive record therefrom and reprintingsaid record upon a non-conduct-ive tape having a liquid coatingcontaining silver in solution and by depositing the silver vfrom saidsolution upon the surface of said tape by hotographic development.

Signed at hicago, in the county of Cook and State of Illinois, this 25thday of July,

HOWARD L. PAGE.

